fix(ts): Correct missing null checks in algolia.ts (#7369)

src/gatsby/utils/algolia.ts

@@ -1,7 +1,7 @@
 /* eslint-env node */
 /* eslint import/no-nodejs-modules:0 */
 
-import fs from 'fs';
+import {promises as fs} from 'fs';
 import {join, resolve} from 'path';
 
 import {
@@ -49,20 +49,21 @@ const flatten = async (pages: any[]) => {
 
  const {context, path} = page;
  const htmlFile = join(pub, path, 'index.html');
- const html = (await fs.promises.readFile(htmlFile)).toString();
+ const html = (await fs.readFile(htmlFile)).toString();
 
  // https://github.com/getsentry/sentry-global-search#algolia-record-stategy
- let platforms = [];
+ let platforms: string[] = [];
+
  if (context.platform) {
- const {slug} = standardSDKSlug(context.platform.name);
+ const slug = standardSDKSlug(context.platform.name)?.slug;
 
  let fullSlug = slug;
 
  if (context.guide) {
- const {slug: guideSlug} = standardSDKSlug(context.guide.name);
+ const guideSlug = standardSDKSlug(context.guide.name)?.slug;
  fullSlug += `.${guideSlug}`;
  }
- platforms = extrapolate(fullSlug, '.');
+ platforms = extrapolate(fullSlug ?? 'generic', '.');
  }
 
  const newRecords = htmlToAlgoliaRecord(